Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C15/00—Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
  • G01C15/002—Active optical surveying means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/481—Constructional features, e.g. arrangements of optical elements
  • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone

Definitions

• the invention relates to an optical range finder, as z. B. be used in the measurement of land and buildings.
• Emission edge emerging light beam has a very long and narrow cross section. This leads to poor target illumination, since only part of the light beam strikes the target and thus affects the range and the measuring accuracy.
• the measurement can also be done by reflecting parts of the beam that miss the target on other, eg. B. distant objects are disturbed.
• the invention is based on the object of specifying a generic optical rangefinder with which better target illumination is achieved than in known rangefinders of the generic type.
• FIG. 1b schematically shows a top view of the transmitter according to FIG.
• FIGS. 3 shows a plan view in the beam direction of a first deflecting element of the transmitter according to FIGS.
• Fig. 4 is a plan view against the beam direction of a second deflecting element of the transmitter according to Fig. La, b and
• FIG. 5 shows the target illumination by the transmitter according to FIG. La, b.
• An optical rangefinder has a transmitter and a receiver, which, for. B. can be constructed in a known manner with optics and avalanche photodiodes, and an electronic control and evaluation unit, likewise of a known design, which controls the transmission of light pulses by the transmitter and evaluates the output signal of the receiver.
• the distance measurement can be carried out by running time measurement or by the phase comparison method.
• the transmitter has a collimator 1 and a light source 2 arranged upstream thereof, which is composed of a laser diode 3 and a beam shaping lens 4.
• the emission edge has a length of between 30 ⁇ m and 800 ⁇ m, while its width is between 1 ⁇ m and 3 ⁇ m.
• the emission edge can also be interrupted in the longitudinal direction.
• a linear arrangement of laser diodes with edge lengths of z. B. 50 microns and distances between successive edges of 100 microns can be provided.
• the numerical aperture which corresponds to the sine of half the opening angle, is parallel to
• SBP space bandwidth product
• the beam shaping optics 4 which comprises a cuboid block 5 made of a transparent material, preferably glass, with a first end face, serve the purpose facing the laser diode 3 and an opposite second end face facing the collimator 1.
• the first end face carries a holder 6 made of plastic, which holds a cylindrical lens 7 at its end regions.
• the cylindrical lens 7 has a round cross section, its diameter is approximately 60 ⁇ m. It is aligned parallel to the emission edge of the laser diode 3 and spaced from it by approximately 10 ⁇ m. It parallelizes the light beam emanating from the emission edge, which crosses a large one in the case of laser diodes of the type used
• the diameter of the cylindrical lens and its distance from the emission edge can also be significantly larger than specified, but with small values, in particular of at most 65 ⁇ m or at most 15 ⁇ m, the overlap of the portions coherently emitted by the successive regions of the edge is very small, which is also keeps the losses caused by the overlap low.
• first deflecting element 8 Downstream of the cylindrical lens 7 is a first deflecting element 8 which is integral with the holder 6 and which forms a structured surface which is essentially planar and parallel to the first end face of the block 5. It breaks up parallel to the emission edge into three successive fields 9a, b, c, which carry different stair-like diffraction structures.
• the end face of the block 5 carries a second deflecting element 10 made of plastic, which has a structured surface which is essentially planar and parallel to the second end face and which breaks down into three successive fields 11a, b, c transverse to the emission edge, which also carry different stair-like diffraction structures.
• the upper field 9a of the first deflecting element 8 is structured such that it directs the partial beam emanating from an upper section of the emission edge, from which it is struck, onto the left field 11a of the second deflecting element 10, as seen in the beam direction, where the beam is deflected slightly so that it falls on collimator 1 and fills approximately the left third of its aperture.
• the lower field 9c of the first deflecting element 8 directs the partial beam emanating from a lower section of the emission edge, from which it is struck, to the right field 11c of the second deflecting element 10, as seen in the beam direction, where it is likewise deflected accordingly and subsequently fills approximately the right third of the aperture of the collimator 1.
• the middle third of the same is filled by the partial beam emanating from a somewhat shorter middle section of the emission edge, which passes undeflected through the unstructured middle fields 9b and 11b of the first deflecting element 8 and the second deflecting element 10, respectively.
• the three partial beams are deflected so differently by the first deflecting element 8 that, viewed transversely to the emission edge, they fall next to one another onto the second deflecting element 10, and consequently their projections on a plane spanned by the direction of the emission edge and the beam direction essentially coincide. They are then deflected differently by the second deflecting element 10 in such a way that they hit the collimator 1 as if they each originated from a line parallel to the emission edge in the focal plane of the collimator 1 or, in other words, so that their rearward extrapolation increases in each case Such a line leads and each sub-beam fills about a third of the aperture of the collimator 1.
• the three consecutive Sections of the emission edge are mapped onto an almost square field, in such a way that they overlap in the far field (FIG. 5). This ensures excellent target illumination.
• the beam can be focused very closely, which allows distance scanning with high lateral resolution. Wavelengths around 1,550 nm are also very advantageous because then the upper limit of the permissible individual pulse energy, given with regard to eye safety, is approx. 8 J by a factor of approx.
• the bracket 6 and the one-piece first deflecting element 8 and the second deflecting element 10 are each produced using one of the replica techniques as described in MT Gale: 'Replication' in HP Herzig (ed.): 'Micro-Optics', Taylor & Francis 1997, pp. 153-177 are described - e.g. B. etching a roll or a stamp made of quartz and hot stamping, injection molding or casting with subsequent UV curing - and glued to the block 5.
• the diffraction structures can be determined using known computer programs.
• the replica process allows inexpensive production of large quantities.
• the fact that the holder 6 is also produced in this technique allows the cylindrical lens 7 to be positioned very precisely.
• the distance tolerance thereof with respect to the first deflecting element 8 is a few ⁇ m.
• the laser diode can continue 3 are connected to the beam shaping optics 4 such that the mounting tolerance between the same and the cylindrical lens 7 is approximately 0.5 ⁇ m.
• the cylindrical lens can be attached directly to the laser diode with putty.
• the first deflection element and the second deflection element can also consist of glass and be produced, for example, by an etching process. They can also be etched directly into the block that separates them.
• the number of fields of the deflecting elements can also be two, four or more instead of three.
• the beam shaping optics can also consist of refractive elements, e.g. B. prisms and plates exist.
• laser diodes with wavelengths above all between 600 nm and 1,000 nm and in particular between 630 nm and 980 nm can also be used, which lie outside the ranges specified above.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Optical Radar Systems And Details Thereof (AREA)
• Semiconductor Lasers (AREA)
• Glass Compositions (AREA)
• Liquid Crystal (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Surgical Instruments (AREA)
• Laser Surgery Devices (AREA)
• Measurement Of Optical Distance (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Photoreceptors In Electrophotography (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

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Citations (7)

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• 2000
  • 2000-04-26 EP EP00108836A patent/EP1150097A1/de not_active Ceased
• 2001
  • 2001-02-28 AT AT01929368T patent/ATE297544T1/de not_active IP Right Cessation
  • 2001-02-28 CA CA002407533A patent/CA2407533C/en not_active Expired - Lifetime
  • 2001-02-28 JP JP2001581055A patent/JP4753341B2/ja not_active Expired - Lifetime
  • 2001-02-28 AU AU5616701A patent/AU5616701A/xx active Pending
  • 2001-02-28 WO PCT/EP2001/002204 patent/WO2001084077A1/de active IP Right Grant
  • 2001-02-28 EP EP01929368A patent/EP1287312B1/de not_active Expired - Lifetime
  • 2001-02-28 DE DE50106457T patent/DE50106457D1/de not_active Expired - Lifetime
  • 2001-02-28 AU AU2001256167A patent/AU2001256167B2/en not_active Expired
• 2002
  • 2002-10-24 NO NO20025113A patent/NO334674B1/no not_active IP Right Cessation

Patent Citations (7)

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